Development of drugs (inhibitors) to control complications associated with diabetes depends on a thorough knowledge of the enzymes associated with alpha and beta-D-glucose metabolism. The kinetic properties of the metalloenzyme, gluconolactonase (E.C.1.1.17) are not sufficiently known to determine its role in gluconic acid formation. This enzyme's primary substrate, 1, 5- gluconolactone, is a potent inhibitor of glycosidases and phosphorylase. Thus, gluconolactonase may well be a major metabolic regulator of membrane development and glycogen retention in hepatic tissue. In this study, we will use polarimetry and high resolution 1H, 13C and Mn FT NMR (300 MHz for 1H) to determine the various kinetic and equilibrium constants associated with this enzymatic reaction. Gluconolactonase requires a divalent metal-substrate complex for catalysis to occur. We will study the effects of Mn2+, Mg2+, Zn2+, Ca2+, Ni2+ and Fe2+ on the structure of the metal-lactone complex and the kinetics of the reaction as a function of pH and temperature. We will use 13C 1-labelled 1, 5- gluconolactone to follow the kinetics of hydrolysis by 13C NMR as has been previously done for the non-enzymatic reaction. Gluconolactonase isolated from rat pancreatic and porcine and bovine hepatic tissue will be used in this study. Once the kinetic properties of gluconolactonase are established, we will calculate the flux of beta-D-glucose to gluconic acid via the enzymes, glucose dehydrogenase and gluconolactonase. This will help us to determine the rate of flow of beta-D-glucose across the endoplasmic reticulum and into the cytosol in the form of gluconic acid.